High Efficiency Quasi-Phase-Matched Optical Parametric Conversion And Dual-Wavelength Optical Parametric Generation

Based on quasi-phase-matching (QPM) technology, optical parametric conversion——including optical parametric generator (OPG) and optical parametric oscillator (OPO)——can be a powerful method to generate widely tunable, high efficient near and mid infrared radiation. The most important part of the researches involved optical parametric conversion is how to make the phase matched. Compared with the traditional birefringent phase matching (BPM) technology, QPM technology's advantages are obvious: collinear phase matching scheme, high conversion efficiency, precise and flexible wavelength tuning methods. Thus, the periodically poled crystals based on QPM technology have been widely used as the frequency converter in the field of nonlinear optics. Besides, because the poled period of the periodically poled crystals can be manually designed, the QPM technology is also widely applied in the generation of terahertz wave radiation (used as dual-wavelength source for difference-frequency-generation or directly used as the generator).The researches discussed in this dissertation are mainly based on the principles of quasi-phase-matched optical parametric conversion. The brief description of the dissertation and some innovative places are presented as follows.1. A high conversion efficiency, low threshold, high-repetition-rate periodically poled lithium niobate (PPLN) OPG was experimentally demonstrated. The conversion efficiency of 62.7% is the highest ever reported.2. We obtained 409 mW average signal power from an actively Q-switched intracavity optical parametric oscillator (IOPO) based on multi-grating PPLN crystal. This output power corresponded to a conversion efficiency of 8.8% with respect to the diode pump power.3. We designed a tunable dual-signal OPG based on multi-grating PPLN by using an acousto-optic beam splitter. The pumping scheme is innovative.4. A dual-wavelength IOPO using two PPLN crystals was designed and experimentally demonstrated. This way of generating dual-wavelength radiation was also firstly reported.5. We theoretically analyzed the tunable parametric generation of terahertz radiation in Slant-Stripe-Type PPLN crystals.6. A model machine of the PPLN IOPO system was designed and produced.